“A Mothers Tail”. A baby cub pulls on his mother's tail to get attention. Photo location: Masai Mara, Kenya. (Photo and caption by Tori Marsh/National Geographic Photo Contest)

People take part in the Classic Ride Rally in downtown Valencia, eastern Spain, 23 November 2014. Some hundred people on classic bikes from the 20's to the 70's participated in the rally. (Photo by Kai Foersterling/EPA)

Spectators cheer as the United Launch Alliance Delta 4-Heavy rocket, with NASA's Orion spacecraft mounted atop, lifts off from the Air Force Station, December 5, 2014, in Cape Canaveral, Fla. (Photo by Smiley N. Pool/AP Photo/Houston Chronicle)

A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)

Finia, a visiting student from Hanover, cools off under a water sprinkler in front of the Chancellery on June 10, 2010 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

The European Football Championship will take place in Donetsk 2012. The city is currently home to two major professional football teams in Ukraine: Shakhtar Donetsk and Metalurh Donetsk, both of which currently play in the Ukrainian Premier League. (Photo by: LancerenoK; Source: Flickr)

In this photo illustration a plastic carrier bag is blown along the road by the wind on March 4, 2008 in Birmingham, England. (Photo illustration by Christopher Furlong/Getty Images)

People feed the birds in Battery Park in the Manhattan borough of New York, December 18, 2014. Hart has been feeding the birds three times a week for the last three years. (Photo by Carlo Allegri/Reuters)